93-04-9Relevant articles and documents
Coal. Kinetics of O-Alkylation
Liotta, Ronald,Brons, Glen
, p. 1735 - 1742 (1981)
The kinetic reactivities of the acidic hydroxyl groups in coal were measured.The chemical action of quaternary ammonium hydroxyde bases in the presence of alkylating agents was used as the probe.Both Illinois No. 6 bituminous and Rawhide subbituminous coals contain aromatic and aliphatic hydroxyls as well as lesser amounts of carboxylic acids.Illinois coal was found to O-alkylate at a faster rate than Rawhide coal.The reactivities of the acidic functional groups in the coals were correlated to the reactivity of acidic groups in model compounds.This was accomplished by both relative and absolute kinetic rate measurements on each coal and a series of model systems.It was discovered that the activation energy associated with the nucleophilic displacement determined the rate of O-alkylation of the coal.Therefore, the rate of the reaction is not limited by mass transport of the chemical reagents into the coal structure.In this sense, O-alkylation of coal is a most unique reaction.
C-H Triflation of BINOL Derivatives Using DIH and TfOH
Nakazawa, Hironobu,Sako, Makoto,Masui, Yu,Kurosaki, Ryo,Yamamoto, Shunya,Kamei, Toshiyuki,Shimada, Toyoshi
, p. 6466 - 6470 (2019)
C-H trifluoromethanesulfonyloxylation (triflation) of 1,1′-bi-2-naphthol (BINOL) derivatives has been established under mild conditions using 1,3-diiodo-5,5-dimethylhydantoin (DIH) and trifluoromethanesulfonic acid (TfOH). Up to eight TfO groups can be introduced in a single operation. The resulting highly oxidized BINOL derivatives can be successfully converted to 8,8′-dihydroxy BINOL and bisnaphthoquinone compounds. Mechanistic studies suggested that C-H triflation occurs in the form of an aromatic substitution reaction via the in situ formation of a radical cation.
Methylation with Dimethyl Carbonate/Dimethyl Sulfide Mixtures: An Integrated Process without Addition of Acid/Base and Formation of Residual Salts
Chan, Bun,Lui, Matthew Y.,Lui, Yuen Wai
, (2022/01/08)
Dimethyl sulfide, a major byproduct of the Kraft pulping process, was used as an inexpensive and sustainable catalyst/co-reagent (methyl donor) for various methylations with dimethyl carbonate (as both reagent and solvent), which afforded excellent yields of O-methylated phenols and benzoic acids, and mono-C-methylated arylacetonitriles. Furthermore, these products could be isolated using a remarkably straightforward workup and purification procedure, realized by dimethyl sulfide‘s neutral and distillable nature and the absence of residual salts. The likely mechanisms of these methylations were elucidated using experimental and theoretical methods, which revealed that the key step involves the generation of a highly reactive trimethylsulfonium methylcarbonate intermediate. The phenol methylation process represents a rare example of a Williamson-type reaction that occurs without the addition of a Br?nsted base.
Method for reducing aromatic C-N/Cl C/I bond to aromatic-H / D
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Paragraph 0028, (2021/09/08)
A method of reducing C an aromatic-N C/Cl/I bond to an aromatic-H / D, the process being a stable aromatic quaternary ammonium salt. After addition of the base and the solvent, the aromatic compound or the deuterated aromatic compound can be efficiently prepared by irradiation with visible light or ultraviolet light. The method can efficiently convert stable aromatic-N/I chemical bonds into aromatic-H / D bonds by visible light or ultraviolet light in a cheap and easily available solvent or deuterated solvent without using a catalyst or a transition metal compound C C. The whole production process is green, environment-friendly, low in cost, wide in substrate applicability, high in yield, high in deuterated rate, simple and convenient to operate, free of explosion risk and remarkable in advantage compared with the conventional production process.
Trialkylammonium salt degradation: Implications for methylation and cross-coupling
Assante, Michele,Baillie, Sharon E.,Juba, Vanessa,Leach, Andrew G.,McKinney, David,Reid, Marc,Washington, Jack B.,Yan, Chunhui
, p. 6949 - 6963 (2021/06/02)
Trialkylammonium (most notably N,N,N-trimethylanilinium) salts are known to display dual reactivity through both the aryl group and the N-methyl groups. These salts have thus been widely applied in cross-coupling, aryl etherification, fluorine radiolabelling, phase-transfer catalysis, supramolecular recognition, polymer design, and (more recently) methylation. However, their application as electrophilic methylating reagents remains somewhat underexplored, and an understanding of their arylation versus methylation reactivities is lacking. This study presents a mechanistic degradation analysis of N,N,N-trimethylanilinium salts and highlights the implications for synthetic applications of this important class of salts. Kinetic degradation studies, in both solid and solution phases, have delivered insights into the physical and chemical parameters affecting anilinium salt stability. 1H NMR kinetic analysis of salt degradation has evidenced thermal degradation to methyl iodide and the parent aniline, consistent with a closed-shell SN2-centred degradative pathway, and methyl iodide being the key reactive species in applied methylation procedures. Furthermore, the effect of halide and non-nucleophilic counterions on salt degradation has been investigated, along with deuterium isotope and solvent effects. New mechanistic insights have enabled the investigation of the use of trimethylanilinium salts in O-methylation and in improved cross-coupling strategies. Finally, detailed computational studies have helped highlight limitations in the current state-of-the-art of solvation modelling of reaction in which the bulk medium undergoes experimentally observable changes over the reaction timecourse. This journal is
